Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA.
Genes (Basel). 2020 Dec 15;11(12):1507. doi: 10.3390/genes11121507.
Genetic resistance remains a key component in integrated pest management systems. The cosmopolitan root-knot nematode (RKN; spp.) proves a significant management challenge as virulence and pathogenicity vary among and within species. RKN greatly reduces commercial bell pepper yield, and breeding programs continuously develop cultivars to emerging nematode threats. However, there is a lack of knowledge concerning the nature and forms of nematode resistance. Defining how resistant and susceptible pepper cultivars mount defenses against RKN attacks can help inform breeding programs. Here, we characterized the transcriptional responses of the highly related resistant (Charleston Belle) and susceptible (Keystone Resistance Giant) pepper cultivars throughout early nematode infection stages. Comprehensive transcriptomic sequencing of resistant and susceptible cultivar roots with or without infection over three-time points; covering early penetration (1-day), through feeding site maintenance (7-days post-inoculation), produced > 300 million high quality reads. Close examination of chromosome P9, on which nematode resistance hotspots are located, showed more differentially expressed genes were upregulated in resistant cultivar at day 1 when compared to the susceptible cultivar. Our comprehensive approach to transcriptomic profiling of pepper resistance revealed novel insights into how RKN causes disease and the plant responses mounted to counter nematode attack. This work broadens the definition of resistance from a single loci concept to a more complex array of interrelated pathways. Focus on these pathways in breeding programs may provide more sustainable and enduring forms of resistance.
遗传抗性仍然是综合虫害管理系统的关键组成部分。世界性的根结线虫（RKN； spp.）是一个重大的管理挑战，因为其毒力和致病性在种间和种内都有所不同。RKN 大大降低了商业甜椒的产量，而育种计划不断开发出针对新兴线虫威胁的品种。然而，人们对线虫抗性的性质和形式知之甚少。确定具有抗性和敏感性的甜椒品种如何抵御 RKN 的攻击，可以为育种计划提供信息。在这里，我们在早期线虫感染阶段对高度相关的抗性（Charleston Belle）和敏感性（Keystone Resistance Giant）甜椒品种进行了转录响应特征分析。在三个时间点上，对具有或不具有 感染的抗性和敏感性品种的根进行了全面的转录组测序；涵盖早期穿透（1 天），通过进食部位维持（接种后 7 天），产生了超过 3 亿个高质量的读数。对位于线虫抗性热点的染色体 P9 的仔细检查表明，与敏感品种相比，抗性品种在第 1 天的上调基因更多。我们对甜椒抗性的转录组分析的综合方法揭示了 RKN 引起疾病的新见解，以及植物为抵御线虫攻击而做出的反应。这项工作将抗性的定义从单一基因座概念扩展到更复杂的相互关联的途径。在育种计划中关注这些途径可能会提供更可持续和持久的抗性形式。
